What are the subtypes of pulmonary arterial hypertension (PAH)?

Updated: Apr 25, 2018
  • Author: Kristin E Schwab, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Pulmonary arterial hypertension (PAH) can be further divided into the following subgroups:

  • Subgroup 1 - Idiopathic PAH (IPAH)
  • Subgroup 2 - Heritable PAH, including those with BMPR2 and ALK2 gene mutations
  • Subgroup 3 - Drug- and toxin-induced PAH (Aminorex, fenfluramine derivatives, and toxic rapeseed oil have been identified as definite risk factors for PAH. [1] Other drugs implicated as possible risk factors for PAH include amphetamine and amphetamine derivatives, cocaine, L-tryptophan, phenylpropanolamine, St. John’s wort, leflunomide, phentermine, mazindol, dasatinib, and interferon.)
  • Subgroup 4 - Conditions with known localization of lesions in the small pulmonary arterioles, which include (1) collagen-vascular disease (scleroderma/ CREST syndrome), (2) congenital left-to-right shunts, (3) portopulmonary hypertension, (4) HIV-associated pulmonary hypertension, and (5) schistosomiasis

Pulmonary veno-occlusive disease (PVOD) and pulmonary capillary hemangiomatosis have been designated as 1’ to reflect the fact that although related, they are clinicopathologically and therapeutically distinct entities from PAH (ref 62)

Of note, while persistent pulmonary hypertension of the newborn was previously classified under group 1 PAH, the 2013 classification schema removed this from group 1 to better reflect the differences between this and other PAH subgroups. The updated schema also moved chronic hemolytic anemia from group 1 to group 5 pulmonary hypertension. [4]

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